Low-mass, bi-directional dc-ac interface unit

Abstract

A DC-AC converter includes a DC-DC converter providing bi-directional conversion between a first DC power signal and a second DC power signal, the first DC power signal being on a first DC bus and the second DC power signal being on a second DC bus. The DC-AC converter also includes an inverter providing bi-directional DC-AC conversion between a third DC power signal and a first AC power signals the third DC power signal being on the second DC bus and the first AC power signal being on a first AC bus.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to an electric power processing device, and more particularly, to a low-mass bi-directional DC-AC power converter. The low-mass, bidirectional DC-AC power converter can be incorporated into, for example, an aircraft power conditioning unit that interfaces generation equipment with various load equipment utilizing independent voltages levels and frequencies.[0002]Many industries can benefit from lightweight power conditioning systems that are also flexible in providing a variety of voltages of different magnitudes and frequencies. One such industry is the aviation industry where advances in aircraft design (both manned and unmanned) are necessitating new electric power system architectures. For example, emerging aircraft have 270 VDC electrical power equipment while still maintaining legacy 115 VAC / 400 Hz or variable frequency equipment. The 115 VAC is generated by a power converter that uses the 270 VDC as its input.[0003]FIG. ...

AI Technical Summary

Problems solved by technology

However, use of transformer 63 in an aircraft is not desirable because the transformer is heavy and awkward (approximately 70 lbs for a 6-10 kVA unit operating at 400 Hz).

An output sine wave that is always positive is a problem if the AC system is “expecting” a neutral referenced AC sine wave, i.e. a sine wave whose values are positive and negative (for example, the legacy AC system is typically 115 VAC / 400 Hz).

This will increase the complexity, cost and weight of the system.

However, this topology also has drawbacks.

In addition, DC-DC converter 86 does not provide bidirectional power flow.

Therefore, an AC source, such as an EPC AC ground cart, cannot be used to generate the DC bus when the aircraft is grounded.

To add bi-directional capability to the topology shown in FIG. 4, additional components and controls must be added to both sides of DC-DC converter 86, which increases cost, complexity and weight.

Accordingly, the related art power conditioning units are awkward and heavy (transformers), do not easily provide bi-directional power flow capability (i.e., without requiring additional components), and / or produce an output voltage supply that is not optimal for an aircraft.

Unfortunately, all these options have their drawbacks.

For the AC ground cart option, the additional circuitry needed to allow the EPC AC ground cart to assist in the main engine start will add additional weight and complexity to the related art power conditioning units.

Although the third option of providing an engine start capable on-board battery will provide this flexibility, the weight and cost of the battery makes this option prohibitive.

In addition, related art power conditioning units are not designed to regulate the power going to the legacy AC bus during main engine start.

Without regulation, main engine starts may create power fluctuations that cause power blackouts in the legacy AC system, which would necessitate longer aircraft commissioning times.

Images